You've saved your pennies, make that dollars and a lot of them, and now you're ready for a new DSLR. Whether it's your first one or if you're upgrading, there's one question that remains the same: What specs matter? From megapixel ratings to ISO to sensor size to full HD video capability, there's a lot to consider. The good news is that nowadays almost, if not all, of the DSLRs out there have most of the basics, it's just a matter of to what extent. Sort of like when all phones were available with caller-ID and call-waiting. Those kinds of features that they bragged about even though it was the norm by a certain time period. The same holds true with DSLRs. Megapixels in the double digits are standard. Things like that. So, let's break the specs down and see what's important to your photography needs and what's a given already.
Like megapixels, there are many advertised specifications that do not indicate image quality, and, the truth is, you're not going to know if a camera can capture incredible photos by its technical details. However, a few of the specs can tell you things about a camera's image quality potential, and they all relate to its sensor. We'll go over megapixels first, but it's the camera's sensor you really want to take note of.
Megapixel ratings are the number of million pixels a camera can capture in a single shot. These days, almost all cameras have double digits of megapixels, making this spec basically irrelevant when it comes to image quality. Some would even argue that a high megapixel rating on a small camera is not such a great idea because if a camera has too many megapixels packed into it, the images can get a noisy (grainy) because there is too much information being captured and stored in a small space. As technology improves, this is not as big of an issue, but it is a good reason not to rely on a camera's megapixel rating.
The sensor in a DLSR is the equivalent of what used to be film in a 35mm camera. The senor is exposed to the available light when you click your shutter speed. It and other components capture and store this data. Because it's the sensor that's capturing and storing your images, this is the most important spec you'll want to consider.
That said, there are numerous camera sensors available. In fact, too many to cover in an article; however, there are a few you should know about before you head out the door or online with your credit card. I'm listing four of the top ones in order from smallest to largest.
Also known as MFT, the Micro-4/3rds Sensors were standardized by Panasonic and Olympus back in 2008. Built as a compromise between DSLRs and point-and-shoot cameras, the Micro-4/3rds system is the most compact. The thought was to provide a more compact system with interchangeable lenses that still produce high quality images. Cameras with this sensor can provide much higher-quality images while keeping to their portable size often found in a compact digital camera.
Advanced Photo Systems - APS-C Sensors
Advanced Photo Systems, APS-C sensors, are commonly used in DSLR cameras. These sensors are significantly larger than what's available in a point-and-shoot camera or a cellphone. Sensors meeting similar dimensions are used in many digital single-lens reflex cameras in addition to some large-sensor live-preview digital cameras, such as the Sony DSC-R1, Sigma DP1 and Leica X1, and some digital rangefinders, like the Epson R-D1).
While smaller sensors struggle with capturing enough light, larger sensors are able to accommodate lower light situations. Another advantage is having better control of depth of field. With a larger sensor, you can more readily render an out-of-focus background behind your subject. APS-C sensors, however, have one common disadvantage, and that's crop factor. Crop factor refers to how a lens is magnified when attached to APS-C-based cameras. For example, if you use a 28mm lens, it would be magnified to look like a 45mm lens. In other words, subjects are zoomed in a little bit more. While this isn't such a big deal, you should be aware of it, especially if you're a landscape photographer who takes a lot of wide images. While a good 28mm lens would look wide enough on a 35mm film or full frame camera, it might be insufficient on a DSLR with an APS-C sensor.
Full Frame Sensors
Full frame sensors are often considered to be the digital equivalents of 35mm film. You'll find these sensors on high-end DSLRs such Canon's 5D series. The most desirable benefit of the full frame sensor is that there is no crop factor. As you just read above, the APS-C sensors have a crop factor that magnifies lenses. But, when it comes to a full frame camera that lens won't be magnified at all. For example, a 28mm lens will give you a 28mm image.
Another big benefit to larger sensors is that they have greater potential for capturing more light. This means they can produce a very shallow depth of field, which is a huge benefit for portrait photographers. You can guess by now that full frame cameras have the ability to produce some of the highest quality images.
In a nutshell: the larger the sensor, the higher-quality images you'll produce. It's not a guarantee; however, you won't often capture a cellphone image that can compete with a DSLR. And, while a camera's sensor can be critical, it's not the only spec to pay attention to.
The Image Processor
A camera's image processor can affect quality in a few ways, many of which are irrelevant if you're shooting in RAW and not JPEG. RAW images are just the data the sensor sees, completely unprocessed. This is great if you want to process the images yourself, later. If you're using a point-and-shoot, or just plan to shoot JPEGs, the processor matters. Many cameras can fix lighting issues and adjust various other settings that can make your images look really nice. A good image processor makes it possible for the camera to handle these operations. It also makes it possible for a camera to capture images in quick succession. While this won't affect image quality directly, being able to capture a few images can mean the difference between getting a good shot and a great shot. A fast processor can actually make a big difference in these ways, so don't disregard it even if you don't need to shoot a lot of photos quickly. A camera's speed is important, as a fast processor can allow a camera to compensate for less-than-ideal lighting conditions.
A good lens can make all the difference in the world in a photograph. Since the lens is the eye of your camera, if it can't see well, i.e. have good optics, your images will reflect this. In the case of point-and-shoot cameras, the optics are limited in quality for two reasons. First, the optics are limited in size, and second, they're fixed to the camera, unlike a DSLR.
So, when looking at DSLRs, consider what the maximum aperture is or how wide the lens opens. We know from basic photography that the wider the aperture, the more light is let in, which means you can take more pictures in low light situations. This all comes down to the f-stops, so when you're shopping for lenses, take note of their f-stops. For example, some 50mm lenses are f/1.4. That means its maximum aperture, or f-stop, if 1.4. This is a pretty standard f-stop for portrait lenses. Other lenses might just be f/3.5, which is pretty common in telephoto lenses.
The bottom line is that before you drop a month's salary (hypothetically) on a DSLR, megapixels aren't as important as considering the sensor size, the optics, and the apertures. Happy shopping!
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